Muchas gracias.
Por lo que veo en este comentario:
"
[FONT=arial,helvetica]In the early 1960s, Rolex once again reached the 999,999 mark, but this time added a 7<SUP>th</SUP> digit and continued until mid 1987, when the numbering reached 9,999,999. At this time, Rolex elected to start numbering with a letter prefix (e.g. R000001).[/FONT]
[FONT=arial,helvetica]The system started with the letter "R", whcih was then subsequently followed by L-E-X. Thus spelling out the word "ROLEX" with the "O" being omitted, to help avert any possible confusion with the number "0". This sequence continued through November 1991, when a new numbering system was introduced utilizing the letters N, C and S, which took them through 1993. In 1994, Rolex started yet another sequence with the letters: W, T and U, then A, P, and K in subsequent years."[/FONT]
La sigla es parte del la referencia del reloj, y cuanto mas avanzado sea este en el abecedario, mas moderno será el reloj.
Un saludo y gracias.